Winding R&D for CFETR Central Solenoid Model Coil

A central solenoid model coil (CSMC) is being developed to verify the large-scale Nb₃Sn superconducting coil manufacture technologies for China Fusion Engineering Test Reactor in ASIPP (Institute of Plasma Physics, Chinese Academy of Sciences). The CSMC composed of Nb₃Sn and NbTi hybrid superconducting magnet can reach to the maximum magnetic field 12 T. All of the Nb₃Sn and NbTi coils are composed of pancakes windings, pancake joggles, and upper and lower leads. For the multipancakes, the radial dimensions are from 1500 to 3544.8 mm and the maximum axial height is 1545.4 mm. High manufacture accuracy must be acquired for coil continuous winding, i.e., the innermost and outermost circular turn surface profile tolerance is 2 mm and the conductor feeding tolerance is 0.5⁰/₀₀L. The winding R&D activities, including the continuous winding for the pancakes and the online forming for the joggles, have been conducted to optimize and finalize the coil design as well as to carry out the coil winding technology verification and improvement. Now, the continuous winding for double pancakes of the Nb₃Sn inner coil has been finished. The details have been described in this paper.